In many applications it is desirable to supply a charging voltage to a lead acid battery. However, as lead acid batteries have a distinct negative temperature characteristic, a battery charger designed to adequately charge a lead acid battery at normal temperature may severely overcharge a battery at higher temperatures or drastically undercharge a battery at lower temperatures. For this reason, battery chargers have been designed that automatically adjust the charger output voltage for temperature variations. The charger is designed to supply a higher charging voltage to the battery at lower temperatures and, conversely, a lower charging voltage at higher temperatures.
However, battery chargers have provided automatic temperature compensation of charger output voltage in the past through the use of thermistor/resistor networks, temperature sensitive resistors or special purpose integrated circuit chargers. While these solutions have aided in reducing the possibility of over or under charging lead acid batteries due to temperature variations in the approximate area of the battery, they are costly and complicated.
Thus, there is a need for a battery charger system that supplies an accurate and predictable charger output voltage to a battery with automatic temperature compensation adjustment of the output voltage. There is also a need for a battery charger system that automatically adjusts the charger output voltage supplied to the battery in an efficient and low cost manner.